X86: Reject register operands with obvious type mismatches.

While we have some code to transform specification like {ax} into
{eax}/{rax} if the operand type isn't 16bit, we should reject cases
where there is no sane way to do this, like the i128 type in the
example.

Related to rdar://21042280

Differential Revision: http://reviews.llvm.org/D10260

llvm-svn: 239309

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -25517,6 +25517,10 @@ X86TargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
         Res.first = DestReg;
         Res.second = &X86::GR64RegClass;
       }
+    } else if (VT != MVT::Other) {
+      // Type mismatch and not a clobber: Return an error;
+      Res.first = 0;
+      Res.second = nullptr;
     }
   } else if (Res.second == &X86::FR32RegClass ||
              Res.second == &X86::FR64RegClass ||
@@ -25542,6 +25546,15 @@ X86TargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
       Res.second = &X86::VR256RegClass;
     else if (X86::VR512RegClass.hasType(VT))
       Res.second = &X86::VR512RegClass;
+    else if (VT != MVT::Other) {
+      // Type mismatch and not a clobber: Return an error;
+      Res.first = 0;
+      Res.second = nullptr;
+    }
+  } else if (VT != MVT::Other) {
+    // Type mismatch and not a clobber: Return an error;
+    Res.first = 0;
+    Res.second = nullptr;
   }
 
   return Res;

llvm/test/CodeGen/X86/asm-reject-reg-type-mismatch.ll

@@ -0,0 +1,10 @@
+; RUN: not llc -no-integrated-as %s -o - 2> %t1
+; RUN: FileCheck %s < %t1
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--"
+
+; CHECK: error: couldn't allocate output register for constraint '{ax}'
+define i128 @blup() {
+  %v = tail call i128 asm "", "={ax},0,~{dirflag},~{fpsr},~{flags}"(i128 0)
+  ret i128 %v
+}